It is known that the pyrazolinone compounds given by the formula (1):
wherein R1 represents a hydrogen atom, chlorine atom or methyl group; R2 represents a chlorine atom or methyl group; R3 represents a 1-methylethyl, 1,1-dimethylethyl, 1-methylpropyl, 1-ethylpropyl or 1-methylbutyl group; and R4 represents a C1-C4 alkoxy, C3-C4 alkenyloxy, C3-C4 alkynyloxy, C1-C4 alkylthio, C3-C4 alkenylthio or C3-C4 alkynylthio group;    are useful as an active ingredient of an agent for controlling plant diseases.
The pyrazolinone compounds given by the formula (1) are known in U.S. Pat. No. 6,294,567, and some granular pesticidal compositions containing the pyrazolinone compounds are known in U.S. Pat. Nos. 6,294,567, 6,521,568 and JP-2002-316902A.